Arlington National Cemetery's deputy superintendent has retired before Army officials could compel him to meet with a Senate Homeland Security subcommittee investigating contracting irregularities, including more than $5 million paid to a series of minority-owned start-up companies that failed to produce a digitized system for cataloguing remains.

Thurman Higginbotham, the cemetery's longtime second-in-command, submitted paperwork last week to make his retirement retroactive to July 2, the week Army officials were notified that congressional staffers were seeking to interview him regarding dozens of botched contracts.

Higginbotham had been placed on administrative leave last month pending disciplinary review after Army investigators found more than 100 unmarked graves, scores of grave sites with headstones not recorded on cemetery maps, and at least four burial urns that had been unearthed and dumped in an area with excess grave dirt. Investigators found that those and other blunders were the result of a "dysfunctional" and chaotic management system, poisoned by bitterness between Higginbotham and the cemetery's superintendent, John C. Metzler Jr.

Metzler was reprimanded last month but was allowed to retire July 2 with full pension benefits. On Tuesday, Higginbotham's eligibility for retirement benefits was not immediately clear. He had worked at Arlington for more than 40 years and served as its deputy superintendent since 1990.

Cemetery spokeswoman Kaitlin Horst said that Higginbotham's retirement was being reviewed but that generally an employee's departure precludes the Army from taking further administrative action.

The Army's investigation of "wrongdoing while Higginbotham was still employed" continues, Horst said.

Most immediately, Higginbotham's departure sets up a potential showdown with the Senate Homeland Security and Governmental Affairs subcommittee on contracting oversight. The committee's chair, Sen. Claire McCaskill (D-Mo.), has scheduled a hearing July 29 into the cemetery's alleged contracting improprieties.

McCaskill spokeswoman Maria Speiser said the subcommittee is seeking Higginbotham's cooperation. "Sen. McCaskill is hopeful that he will do so voluntarily," Speiser said. "At this point, he has not indicated otherwise."

But Higginbotham's attorney, Robert W. Mance, said he was not aware that the committee has contacted Higginbotham. "If he is contacted, the question remains as to whether he is even obligated at this point to testify," Mance said.

"Mr. Higginbotham was basically due to retire anyway. And as far as what's going on over there, and all of the accusations that have been thrown at him -- all of these contracts and all of these things -- people have information," Mance said. "They know why those contracts weren't completed, and that had nothing to do with Mr. Higginbotham." Mance declined to elaborate when asked whether he was suggesting that others were involved in wrongdoing.

The Army inspector general's report released June 10 said that the deputy superintendent was at the center of contracting irregularities. The report found that although Higginbotham had no training or authority as a government contracting officer, almost three dozen contracts listed him as the government contact monitoring performance on technology contracts to digitize records for the cemetery's 330,000 interred remains.

Most contracts lacked required government analysis to determine whether companies were charging "fair and reasonable" prices. And none included the most basic government language requiring that contractors be "trained, qualified and certified to maintain and protect" government computer systems, the inspector general found.

Under that loose system -- which the inspector general found was not inspected or audited for more than 10 years by officials up the Army's chain of command -- the price for contracted work sometimes doubled, and none of the contracts produced a usable system to replace the cemetery's centuries-old method of verifying interments using 3-by-5 cards and other paper records.

Over the past year, Higginbotham had remained as deputy superintendent, with day-to-day control over almost all aspects of the cemetery, according to government documents. He remained despite an Army criminal investigation that found that he had made "false and misleading statements to agents" regarding access to a fired employee's e-mail account and a government computer in 2008.

Higginbotham had sought control of computer records for Gina Gray, a former public affairs officer, after she filed an equal employment opportunity complaint. Agents found that someone had accessed Gray's computer and sent an e-mail impersonating her on a morning that Higginbotham and a contract technology employee were in the cemetery's administrative building. But investigators said they could not prove who accessed Gray's computer.

Mance said Higginbotham was innocent. "That e-mail bit, there's absolutely no truth to Mr. Higginbotham being involved," he said. "For over a year we've tried to cooperate, and all we get are more accusations."